Leonid Meteors Active Early Tuesday Morning

This is the time for the Leonids meteors, that middle-of-November, middle-of-the night celestial light show. These ultra-swift light streaks appear to emanate from out of the constellation of Leo (hence the name, “Leonid”), which begins to rise in the northeast around 11 p.m., then gradually ascends the sky, remaining in view for the balance of the night.

Three images of the after-effects of a single Leonid meteor toward the constellation Cassiopeia. Shortly after a brilliant fireball streaked across the sky, the meteor's train lasted more than 5 minutes. The first image was taken about 15 seconds after the fireball appeared. The second image was made about 1 minute after the fireball appeared, and the last image was made 5 minutes after the meteor first showed up. Wind in the upper atmosphere distorted the trail.

Credit: Joe Rao

The meteors usually reach their peak each year on Nov. 17 or 18 as Earth travels through streams of dust left behind by the comet Tempel-Tuttle. Tempel-Tuttle orbits the Sun every 33-years, and during its closest approach the heat of the Sun causes some of the comet’s ice to bubble off, taking some dusty debris with it; stray bits of comet matter that go whipping through the solar system.

The average Leonid that is visible to the naked eye, is scarcely larger than a grain of sand. We know them best when they reach the Earth’s upper atmosphere and flare into streaks of light from friction with the rarefied air. They enter with an immense velocity—45 miles per second, or 162,000 miles per hour—and its kinetic energy is used up in such processes as the instantaneous production of light, heat and ionization.

Thus, such a small particle can be seen as a “shooting star” from more than 100 miles away. Obviously, however, it's really the light energy that it develops and not the particle itself that we see.

This year the best time to look for the Leonids will not be on the traditional nights of Nov. 17 or 18, but rather in the early morning hours of Tuesday, Nov. 20. Two reputable experts in the field of meteor science, Jeremie Vaubaillion of France and Mikhail Maslov of Russia, have independently calculated that the Earth is on target to pass directly through a small clump of dust that was shed by comet Tempel-Tuttle when it swept around the Sun back in the year 1400. That interaction is to occur between 12:30 a.m. and 4:00 a.m. EST.

This year the best time to look for the Leonids will not be on the traditional nights of Nov. 17 or 18, but rather in the early morning hours of Tuesday, Nov. 20. Two reputable experts in the field of meteor science, Jeremie Vaubaillion of France and Mikhail Maslov of Russia, have independently calculated that the Earth is on target to pass directly through a small clump of dust that was shed by comet Tempel-Tuttle when it swept around the Sun back in the year 1400. That interaction is to occur between 12:30 a.m. and 4:00 a.m. EST.